The Yazidis, a small Iraqi minority who believe in a single god who created the Earth and left it in the care of a peacock angel, have been subjected to large-scale persecution by ISIS, which accuses them of devil worship.

The United Nations has accused ISIS of committing genocide against the Yazidis.

The families of many of the missing have reached out to Hasan for help.

"People know me," she explains. "I am from Sinjar and also I am Yazidi. I know many people who were kidnapped. Some were my relatives, my neighbors, and they called me."

Together with her husband, Khalil, Hasan manages a network to smuggle the women out: she takes the calls, and Khalil makes the dangerous journey to the Iraq-Syria border to bring them to safety.

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So far, the couple has rescued more than a hundred people. One of the first was a 35-year-old woman with six children -- all of whom had been captured, bought and sold in ISIS' slave markets.

In her desperate call to Hasan, she described what had happened to them: "They loaded two big trucks from the village and took them somewhere, I don't know where. When they were loading people on to the truck, a woman started arguing with them, so they killed her."

Despite her horrific ordeal, the kidnapped woman in this recording was one of the lucky ones -- she got out, eventually.

Others are not so fortunate. Hasan says many women, repeatedly raped and abused by their captors, have taken their own lives rather than wait to be saved.

"We just want them to be rescued," she says, through tears of sadness and frustration. "Hundreds of girls have committed suicide.

"I have some pictures of the girls who have committed suicide ... when they lose hope for rescue and when ISIS many times sell them and rape them ... I think there is maybe 100. We lost contact with most of them."

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U.S. Secretary of State John Kerry praised her "courageous efforts on behalf of the Yazidi religious minority in northern Iraq, for insisting that the world give heed to the horrors that they face, and ... firm commitment to helping the victims and saving lives."

But she is haunted by the thought of those she could not save.

"I cannot sleep, I cannot forget what has happened to them," she says.

"[They ask] When will you rescue us? But I don't have the answer. I'm not a government. I'm not anything. I'm just people. It's very difficult."

Many have joined the fight against ISIS; instead of bombs and bullets, Hasan's weapon is her phone; with it, she offers hope, however distant, and a promise that help is coming.